Used as a form of negative reinforcement. A hand job where the giver covers their hand in vaseline, followed by dipping the hand in beach sand. This results in massive erosion of the penis.
Marco if you don't clean up your shit, I'm going to give you the roughest sandy handy.
a malevolent maneuver during the delivery of a hand-job wherein the performer edges the unsuspecting recipient into a swoon of ecstasy before swiftly and discreetly dipping their lubed hand into a concealed stash of sand and resuming the hand-job, chaffing the recipient's penis
She gave him a sandy handy while they were at the beach.